I do like mindmaps. Sometimes, I'm a fan. For me drawing goes better with a paper and a pen (real paper and real pen). But result could be stored in a file as well.
The Internet recommended me a free mind map editor called FreeMind. I find it very reasonable, especially for the money (it is absolutely free). It works on windows and linux - the systems I do use.
Looks like there it is not ported to android but I had no wish to work with mindmaps on my smartphone so far (meanwhile for tablet users it could be an issue).
Actually, as far as I remember I found no alternatives for it.
As I already mentioned FreeMind works well for me.
Using FreeMind I discovered only one significant issue.
I created a mind map in windows version of FreeMind and later on tried to open it in my ubuntu version. It said that the file was created with older version of FreeMind and is now converted. Afterwards... right it showed me an empty map.
Actually, Ubuntu FreeMind version was older than windows version: 0.9.0 against 1.0.1.
In Ubuntu I installed FreeMind from the application center - the way FreeMind told me to go.
This looks strange, especially keeping in mind that FreeMind 1.0.0 was released in 2013.